code: def forward_expected(self, inputs):
      (x,) = inputs
      expected = _maxout(x, self.pool_size, self.axis)
      assert expected.shape == self.y_shape
      return (expected,)
  
file_path: chainer/tests/chainer_tests/functions_tests/activation_tests/test_maxout.py
imports: import unittest
  import numpy
  import chainer
  from chainer import functions
  from chainer import testing
  from chainer.testing import attr
  from chainer.utils import type_check
label_desc: Use image node_id 3 for calling the TestNonparameterizedMaxout obj's underlying member method code with example usage: obj.forward_expected(inputs) and returns: expected